Well, I think it is always a complicated matter to expect people to tell you what you might actually want to know about their lives. I think of Simone de Beauvoir, for instance (a very different character from Gertrude Stein). But even leaving other things aside, people have a very short memory for pain. If they feel it too intensely they might remember it physically as trauma, it certainly may remain part of their lives, but it's not necessarily that they would be able to access it so readily when they think leisurely back and prepare to tell a story. Emerson says that great people have the shortest biographies -- they grind all their experiences into paint.
I always appreciated the spot in London in the National Gallery with the two self-portraits of Rembrandt facing each other across the room, 30 years apart...
In any case, I liked the quotation you cited very much. I suspect that also in the lives of certain gifted people I know, something like this is true. Not out of wedlock pregnancies, but perhaps other relationship issues: provoking break-ups through uncharacteristic behavior which they were upset with themselves about for years, or becoming attached to forceful personalities who would demand from them a certain devotion to work which they otherwise couldn't bring themselves to do, not to mention dating unsuitable people... Or even just longstanding frustration with certain aspects of self (intense sensitivity, inability to act "correctly" in certain ways) until it was understood how these might also be gifts.